Dihydroquinazolinone based "turn-off" fluorescence sensor for detection of Cu super(2+) ions

A strategy for the synthesis of a dihydroquinazolinone derivative, 2-(pyridine-2-yl)-2,3-dihydroquinazolin-4(1H)-one and its application in selective recognition of Cu super(2+) ions has been developed. The sensor shows "turn-off" type paramagnetic fluorescence quenching towards Cu super(2+) ions. The binding constant (K sub(a)) of Cu super(2+) ions with the sensor was found to be 8.02 10 super(4) M super(-1) and binding stoichiometry was determined to be 1:1 based on the Job's plot analysis. The sensor can detect up to nanomolar (0.1 nM) level of Cu super(2+) ions from tap water. The single crystal of the QZP.Cu super(2+)Cl.H sub(2)O complex was characterized using X-ray diffraction and the paramagnetic nature of Cu super(2+) was manifested by electron spin resonance (ESR) spectroscopy.